1. Field of the Invention
This invention relates generally to a lancet dispenser assembly, and more specifically, to a lancet dispenser assembly composed of a base component, a clip component containing a plurality of disposable lancets for bleeding small animals, a rectangular, open-ended cover or chamber component enclosing the clip of lancets and serving to hold the clip and lancets during the sterilization process and to allow for maintaining the lancets until their transfer to the dispenser unit component, a dispenser unit component, wherein the clip is held after transfer from the cover component and from which the lancets are dispensed, one at a time, and a top weight component. An integral element of the dispenser unit component is a rubber escapement device which controls or directs the movement of the lancets allowing them to be released one lancet at a time. The dispenser unit is positioned on the base component of the dispenser assembly enabling the lancets to be removed easily. The entire lancet dispenser assembly can be sterilized.
2. Description of the Relevant Art
Biomedical research using small animal models has contributed tremendously to the improvement of human and animal health. Small animals, most prominently rodents, provide an inexpensive platform for biological investigation as well as testing procedures and pharmaceuticals for safety and efficacy. Use of laboratory rodents has become more carefully regulated over the past several decades to insure that animal care and use in the research setting is as humane as possible. Researchers in all aspects of biology and medicine are governed by institutional animal care and use committees (IACUC) that insure the most humane use of these animals as possible.
One very important aspect of rodent models in research is the acquisition of blood samples for testing. Because of the small size of the animals, drawing blood samples is a challenge to the investigator. A number of methods are employed that pass the review of an IACUC, but none are particularly humane or simple. For example, in the USA, the most common bleeding method is retro-orbital, puncturing the orbital sinus behind the eye. This method consistently yields a reasonable blood volume when the investigator is experienced and practiced. (2002. Laboratory Animal Medicine, 2nd Edition, Fox et al., eds., Elsevier Science, New York, N.Y.). However, this method is banned in a number of countries because it is not considered humane.
A second common method is cardiac puncture. This procedure requires anesthesia, which may alter parameters of the experiment. Briefly, a small gauge needle is inserted into the ventricle and blood is slowly drawn out. This procedure requires an extremely practiced investigator and often animals do not survive the process. Again, this procedure is not simple and is only humane when the procedure goes very well with minimal damage along the needle track. Because the chance of losing animals is so prominent, investigators often use an inflated number of animals to accommodate loss during an experiment.
A third more simple method of bleeding mice is the tail clip. A piece of the tail is excised and blood harvested from the severed tail vein. This can be done repeatedly for a few sequential bleeds. The draw back is, that in order to leave enough tail for multiple future bleeds, only a small piece of tail is cut yielding a small blood sample of only a few drops (0.1 ml). This method is easily done without anesthesia. However, this procedure may not be considered humane, especially for multiple blood draws.
Finally, a method which is more humane and done without anesthesia is the saphenous vein puncture (Hem et al. 1998. Laboratory Animal 32: 364-368). This is a more complicated and time consuming method that involves immobilizing the animal with the rear legs accessible. The hair is shaved from the thigh using a small scalpel or razor. The saphenous vein of the thigh is evident and can be punctured with a 23 to 25 gauge needle. Blood is collected with a microvette capillary collection tube. These vessels have a maximum volume of 0.3 ml. A compress is held on the site to stop the bleeding.
This is a very humane method of blood collection; and since no anesthesia is required, there are no side effects to consider. However, this procedure requires extensive time working with each animal and is not compatible with large trials of pharmaceuticals or biologicals. The man hours required to do a large trial, 50 to 100 animals, would cause researchers to design smaller experiments using fewer animals. The investigators describing this method limit the amount of blood collected to 0.3 ml and in practice, usually less. Therefore, this would yield approximately 0.1 ml of serum and limit analysis to a few very small volume assays.
Thus, there is a need for an improved humane method of bleeding mice where utilization of the method can lessen the need for using large numbers of animals to compensate for animal losses and where utilizing the method allows for testing the animal as often as necessary, including sampling more than one time per day, and yields blood samples of sufficient volume for testing all necessary parameters. The blood lancet of our original invention, Ser. No. 10/967,796, satisfies all the above needs; however, the individual packaging presents another problem. Very often, large numbers of animals are being bled and/or the animals are being bled in a laminar flow hood or in a glove-box. Under such conditions, individually-wrapped sterile lancets are neither convenient nor expedient to use. In these instances, while it is necessary that the lancets be sterile, they cannot be manipulated easily if they are individually wrapped. Thus, there is a need for a device to easily dispense unwrapped lancets where the device and lancets can be sterilized on site.
In the art related to blades, e.g., razor blades, utility blades, or microtome blades, a variety of apparatuses are known for dispensing a single blade at a time from a stack of blades. For example, U.S. Pat. No. 4,789,080 to Iten discloses a utility blade dispenser formed to expose the side edge of a utility blade while it is still at the bottom of the stack of blades within the dispenser, so that a sideways pushing force may be applied by a person's finger to separate this bottommost blade from the stack. U.S. Pat. No. 4,826,042 to Vujovich discloses a blade dispenser with a knob that a person slides to eject a blade from the dispenser. Similarly, U.S. Pat. No. 6,796,455 to Schmidt discloses a blade dispenser assembly which includes a housing and an integrally formed shuttle mechanism which functions to dispense one blade at a time from the bottom of a stack of blades held with the housing and U.S. Pat. No. 6,763,972 to Graupner discloses a microtome knife dispenser which comprises a housing for the reception of multiple knives arranged in a stack wherein a spring is arranged for biasing the knife stack against the inside of the housing cover and a slider is provided to travel with a groove on the outside of the housing cover for engaging an individual knife. Gringer (U.S. Pat. No. 5,409,133) discloses a blade dispenser which includes a housing having side and end walls which define a cavity for storing and dispensing razor blades wherein the open top of the dispenser includes rails along the tops of the sidewalls for guiding the blades out of the housing. A resilient arm integral with the housing is located below the razor blades for applying an upward force on the razor blades against the rails and for aligning a blade to be dispensed with the dispensing slot. McCarthy (U.S. Pat. No. 5,139,167) discloses a blade magazine for storing, transporting and dispensing individually a large number of single edge safety blades. The magazine is essentially an elongated rectangular box having an opening at the base of one wall and thumb-shaped recess along the bottom wall for dispensing a single blade at a time out of the slot in the bottom of the box. A small magnet is disposed on the outside wall and acts to stabilize the blades in the magazine and also to assist in dispensing.
These devices are not suitable devices for dispensing lancets for bleeding mice under such conditions where many animals are being bled or where the bleeding is taking place under, for example, glove box conditions because of a variety of deficiencies with respect to dispensing the lancets of the invention. For example, the dispenser of Iten (U.S. Pat. No. 4,789,080) exposes the side of the utility blade and the blade is removed from the bottom of the stack. These properties preclude utilizing such an apparatus to dispense the lancet of the invention. A quality of the lancet of the invention is that it is manufactured from extremely clean degreased steel; therefore, an additional accommodation or element is required to allow them to become separable. The dispenser of Vujovich requires a knob which one slides to eject the blade; however, one-handed manipulation is required to obtain a single lancet when bleeding animals under laboratory conditions described above because the other hand is usually holding the animal being bled. The dispenser of Vujovich precludes such manipulations, as do the dispensers of Schmidt, Graupner, Gringer, and McCarthy. Such devices are not suitable for dispensing the lancets of the invention because said dispensers have integral parts, e.g., sliders and springs, resilient arm and rails, and magnets, which cannot be used with the lancets of the invention and which are not convenient to use in the laboratory environment. In addition, these dispensing devices do not allow for easy retrieval of lancets of the design of the invention and may be compromised by the process of steam sterilization required for use in animal colonies or isolation hoods.
Thus, while various dispensing devices have been developed to dispense various types of blades one at a time, there still remains a need in the art for a more effective device for dispensing a lancet of the design of the invention for using in bleeding laboratory animals under laboratory conditions. Under such conditions, where large numbers of animals are bled at a time, e.g., for archival or validation purposes or where this involves bleeding large numbers of animals in a hood or glove-box and where laboratory personnel are wearing protective (e.g., rubber, latex, etc.) gloves, sterile lancets must be easily obtainable using only one hand. To date, there is no lancet dispensing apparatus that conveniently and expediently dispenses sterile lancets suitable for bleeding animals, particularly mice. Therefore, a lancet dispenser and associated lancet clips which can be easily sterilized by steam autoclave or other means, which is both convenient and safe to use in a laboratory environment, and which allows for the removal and reloading of lancets easily while wearing gloves and using only one hand, is needed.
The present invention described below solves the drawbacks related to prior art devices currently used for dispensing blades.